Effect of Doping Rare-Earth Element on the Structural, Morphological, Optical and Photocatalytic Properties of ZnO Nanoparticles in the Degradation of Methylene Blue Dye

Abstract

ZnO has been widely explored as a remarkable photocatalyst for the degradation of wide ranges of organic pollutants. However, its photocatalytic activity could be enhanced through metal doping. In this study, a rare-earth element, Cerium was doped into the microstructure of ZnO nanoparticles (NPs) using deposition precipitation method to enhance its photocatalytic activity towards methylene blue degradation via UV light irradiation. The resulting degradation efficiencies (DEs) recorded in this study are ∼ 64 %, 85 % and 55 % respectively. Similarly, the recorded rates are also found to be 9 x 10 −3, 21 x10 −3 and 6 x 10 −3 respectively, which are well correlated with the DE values. This superior photocatalytic performance achieved by 1 % Ce doping could be attributed to the reduction in band gap of the pure ZnO NPs from 2.69 eV – 2.60 eV. Therefore, 1 % Ce was the optimum doping of Ce4+ ion into ZnO microstructure, which demonstrates that Ce4+ ion could be used as an effective tool for stabilizing the generation of the reactive oxygen species, slowing down the recombination of the photo-generated charge carriers as well as enhancing their separation. Therefore, the optimum Ce doping into the ZnO NPs could play a remarkable role in facilitating the structural, microstructural, optical and electronic properties of the ZnO semiconductor, and eventually enhanced its photocatalytic activity.